Gum-massaging oral brush

ABSTRACT

An oral brush is provided that includes an elongated body, a head portion extending from the body, and a plurality of bristles, formed of particular thermoplastic elastomers, extending from the body. In various embodiments, the thermoplastic elastomer has a Shore A hardness of at least 30; the thermoplastic elastomer is selected from the group consisting of polyetheramides, polyesters, styrene-ethylene-butylene-styrene block copolymers, polyurethanes, polyolefin elastomers, and mixtures thereof; and the thermoplastic elastomer has a flexural modulus of at least 5 MPa.

BACKGROUND OF THE INVENTION

[0001] The invention relates to oral brushes and bristles for use inoral brushes.

[0002] Most humans suffer from tooth decay and/or gingivitis caused bybacteria in the mouth. As a result, decreasing the amount of plaque inthe mouth has long been the target of persons working in the health carefield. A common way of minimizing the plaque in the mouth is to brushthe teeth regularly.

[0003] However, the benefits of frequent brushing can be accompanied insome instances by deleterious side effects such as irritation, abrasionand even recession of the gums. These side effects may, in part, resultfrom excessive stiffness and/or sharpness of the toothbrush bristles.

[0004] Another common way of improving oral health is by massaging thegums to stimulate the gingival tissue. Conventional toothbrushes tend tohave limited effectiveness for gum-massaging, and thus often a separategum-massaging procedure, using a gum-massaging tool, is required toensure good oral health.

[0005] Endeavors have been made to reduce gum irritation and/or providea gum-massaging effect by replacing some or all of the toothbrushbristles with rubber or synthetic rubber pins. See, e.g., U.S. Pat. No.4,288,883.

SUMMARY OF THE INVENTION

[0006] The invention features improved gum-massaging oral brushes whichprovide good comfort and gum stimulation while also providing goodcleaning of the teeth. The invention also features bristles for use ingum-massaging oral brushes.

[0007] In one aspect, the invention features an oral brush including anelongated body, a head portion extending from the body, and a brushportion including a plurality of bristles formed of a thermoplasticelastomer extending from the body. The thermoplastic elastomerpreferably has a Shore A hardness of at least 30; is selected from thegroup consisting of polyetheramides, polyesters,styrene-ethylene-butylene-styrene block copolymers,styrene-butadiene-styrene block copolymers, styrene-isoprene-styreneblock copolymers, polyurethanes, polyolefin elastomers, and mixturesthereof; and has a flexural modulus of at least 5 MPa.

[0008] Preferred oral brushes further include a plurality of bristlesformed of a non-elastomeric material. In preferred embodiments, thismaterial is selected from nylon, polyamides, polyesters andpolybutyleneterephthalate (PBT). The non-elastomeric bristles mayinclude additives to improve their cleaning ability, e.g., abrasives andpolishing agents such as clays, silicas, aluminas, calcium carbonate,calcium or magnesium phosphate compounds, apatites, and mixturesthereof.

[0009] Preferred oral brushes also include a spacer attached to the baseof the head portion. The spacer is formed of a thermoplastic elastomerand is integrally joined to the bristles. Preferably the non-elastomericbristles extend from the head portion through the spacer.

[0010] In another aspect, the invention features an oral brush includinga plurality of bristles formed of a thermoplastic elastomer, and aplurality of bristles formed of a polyphthalamide.

[0011] In another aspect, the invention features massaging the gums withone of the bristles described previously.

[0012] An oral brush, as used herein, is any brush that includes a bodyhaving a brush portion designed for insertion into the mouth. The brushportion includes a plurality of bristles extending therefrom and beingdimensioned to be used to brush tooth surfaces.

[0013] In another aspect, the invention features an oral brush includingmulticomponent bristles, preferably comprising a thermoplastic elastomersheath surrounding a core material comprising a non-elastomeric materialor a thermoplastic elastomer having a higher hardness than thethermoplastic elastomer sheath. The invention also features methods ofmaking multi-component bristles, e.g., by coextruding a plurality ofpolymers. By “multicomponent”, we mean that the bristles have two ormore components; by “coextruded”, we mean that at least two of thecomponents are present in the form of substantially separate phaseshaving a distinct interface between them, rather than being intermixed.The bristles are preferably formed by processes which are referred to inthe art as “coextrusion”, but the term “multicomponent coextruded”, asused herein, encompasses bristles having the structure described abovewhich are manufactured by other processes.

[0014] The term “thermoplastic elastomer”, as used herein, refers tonon-vulcanized, rubbery polymeric materials which may be processed byconventional plastics processing methods which are well known in theart, such as extrusion or injection molding.

[0015] In another aspect, the invention features an oral brush includinga plurality of bristles formed of a mixture including (a) anon-elastomeric polymer, such as a relatively hard base resin, e.g.,Nylon, polypropylene, or polybutylene terephthalate (PBT) and (b) athermoplastic elastomer such as a polyamide thermoplastic elastomer, apolyester thermoplastic elastomer or other olefinic thermoplasticelastomers. In some embodiments this mixture also contains additivessuch compatibilizers, abrasives and plasticizers.

[0016] In yet another aspect of the invention, the invention features anoral brush including a plurality of bristles formed of a mixtureincluding (a) a non-elastomeric polymer and (b) a soft (e.g., having ahardness of less than 90 Shore A) vulcanized rubber-type polymer, suchas natural rubber, crosslinked polybutadiene, crosslinked polyacrylatesand the like. In some embodiments this mixture also contains additivessuch as compatibilizers, abrasives and plasticizers.

[0017] Other features and advantages of the invention will be apparentfrom the description of the preferred embodiment thereof, and from theclaims.

BRIEF DESCRIPTION OF THE DRAWINGS

[0018]FIG. 1 is a perspective view of a oral brush.

[0019]FIG. 2 is a schematic top plan view of the head of an oral brushaccording to one embodiment of the invention.

[0020]FIG. 3 is a schematic top plan view of the head of an oral brushaccording to another embodiment of the invention.

[0021]FIG. 4 is a cross-sectional top view of a co-extruded bristleaccording to one embodiment of the invention.

[0022]FIG. 5 is a schematic diagram showing a process according to oneembodiment of the invention for forming a coextruded filament.

[0023]FIGS. 6 and 7 are perspective views of oral brushes havingbristles molded to a spacer.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] Referring to FIG. 1, a toothbrush 10 includes a plastic bodyhaving a handle 12 and a head 14 attached to a bristle portion 16.

[0025] The body of the toothbrush is formed by conventional methodswell-known in the art. The handle is shaped to be grasped by a hand, butalternatively can be shaped to fit into an electric toothbrush. Theconfiguration of the head can vary and may be rectangular, oval,diamond-shaped, or any other shape, with bristles which are trimmedflat, serrated, v-shaped, convex curved, or any other desiredtopography, as is well known in the art. The shape and size of handle 12and head 14 can vary and the axes of the handle and head may be on thesame or a different plane. It may be desired to provide a larger headthan is conventional, in order to provide extra room for thethermoplastic elastomer bristles, while still retaining the standardnumber of non-elastomeric bristles.

[0026] Brush portion 16 includes a number of non-elastomeric bristles 18and a number of elastomeric bristles 20. Preferably, as shown in FIG. 2,the non-elastomeric bristles extend from the central portion of the head14 and the elastomeric bristles are disposed around the outer perimeterof the head 14, surrounding the non-elastomeric bristles. Anotherpossible arrangement is shown in FIG. 3.

[0027] The non-elastomeric bristles are formed of tufts of individualfilaments attached to the head in manners known to the art. Theelastomeric bristles are formed of tufts of one or more filaments ofthermoplastic elastomer. If a single filament is used per tuft, thefilament preferably has a diameter that is half that of a standardpre-cored tuft hole, e.g., 33 mil for a 66-mil pre-cored hole, so thatthe filament can be folded and staple tufted into the hole.

[0028] Alternatively, some or all of the bristles are formed of amixture of elastomeric and non-elastomeric polymers. The elastomericmaterial is selected from the group consisting of thermoplasticelastomers and vulcanized rubber-type polymers. In both cases, the ratioof the elastomer to the non-elastomeric material is preferably from10:90-90:10. Preferred bristle diameters range from 3-100 mil (taperedor untapered), depending on the mixture used and elastomer andnon-elastomeric material chosen as would be understood by one skilled inthe art.

[0029] Suitable filaments formed of a blend of elastomeric andnon-elastomeric include, but are not limited to the following:Processing Drawdown Bend Composition Temp Ratio Diameter Recovery 30%Pebax 2533 250° C. 4:1 8 mil 95% 70% Zytel 151L 30% Pebax 2533 250° C.4:1 7 mil 95% 70% Zytel 151L

[0030] Such a mixture can be compounded using standard processingprocedures such as a single screw or twin screw extruder or dryblending.

[0031] Suitable thermoplastic elastomers are those which have sufficientstiffness and hardness for effective gum massage and to resist tearingand/or excessive wear during use, while being sufficiently soft toprovide comfort and avoid gum irritation during gum massage. Suitablethermoplastic elastomers include polyetheramides, e.g., PEBAX polymers(ELF Atochem); polyesters, e.g., HYTREL polymers (DuPont);styrene-ethylene-butylene-styrene block copolymers,styrene-ethylene-propylene-styrene block copolymers,styrene-butadiene-styrene block copolymers, and styrene-isoprene-styreneblock copolymers, e.g., KRATON rubbers (Shell); polyurethanes, e.g.,PELLETHANE polyurethanes (DOW); polyolefin elastomers, e.g., SANTOPRENEelastomers (Advanced Elastomer Systems); and mixtures thereof.Poly(ether-amide) block copolymers having the general formula

[0032] where PA=polyamide segment and PE=polyether segment, commerciallyavailable under the tradename PEBAX polymers, are particularlypreferred. Of these, a copolymer of nylon 12 and poly(tetramethyleneglycol) having the general formula

[0033] commercially available under the tradename PEBAX MX-1205 polymeris particularly preferred. Another preferred thermoplastic elastomercomprises a blend of a polyamide sold under the tradename PEBAX 2533 anda block copolymer sold under the tradename KRATON G-6713, preferablycontaining about 90% of the polyamide and 10% of the block copolymer.This blend provides good softness without tackiness or weakness.

[0034] If a relatively soft thermoplastic elastomer is used, arelatively large diameter filament may be needed to provide sufficientdurability and stiffness. Such large diameter filaments preferably havea diameter less than about 200 mil, more preferably 30 to 100 mil. If aharder, stiffer thermoplastic elastomer is used, a smaller diameterfilament can be used. Generally, suitable thermoplastic elastomers willhave a Shore A hardness of at least 30, preferably from about 35 to 55and a flexural modulus of from about 5 to 100 MPa.

[0035] Suitable vulcanized rubber type polymers include, but are notlimited to, natural rubber, crosslinked polybutadiene, cross-linkedpolyacrylates, and blends thereof.

[0036] Non-elastomeric bristles 18 may be formed of any materialsuitable for use in toothbrush bristles. Such materials can also be usedas the non-elastomeric component of elastomeric non-elastomeric blendbristles. Preferred materials include nylon 612 and other polyamides. Apreferred grade of nylon is available from Whiting Co., Burlington, Vt.under the tradename WYTEX. Preferred polyamides include polythalamidessold by Amoco Performance Products, Inc., under the tradename AMODELresins. Such polyphthalamides are described in U.S. Pat. Nos. 4,603,166,4,476,280, and 4,617,342, the disclosures of which are incorporatedherein by reference. A particularly preferred polyphthalamide is acrystalline polyphthalamide formed by polymerization of terphthalicacid, isophthalic acid and adipic acid with hexamethylene diamine. Othersuitable filaments include acetal resins, polyesters, fluoropolymers,polyacrylates, polysulfones and combinations thereof. Preferrednon-elastomeric filaments have a diameter of from about 3 to 10 mil.

[0037] In an alternate embodiment, the elastomeric bristles include asheath 30 of thermoplastic elastomer coextruded around a core 32 of adifferent material, as shown in cross-section in FIG. 4. The sheath tocore volume ratio may be from 95:5 to 5:95.

[0038] Preferably, the core material is a stiff polymer, allowing theouter sheath to be softer and/or allowing the bristles to have smallerdiameters than would otherwise be possible (with a thermoplasticelastomer alone) due to the constraints of bristle durability andstrength. If desired the coextruded filaments can have standard bristlediameters, e.g., 5-8 mil. Preferred filament diameters range from 5 to65 mil, depending on the application in which the bristle is to be used.Suitable core materials include but are not limited to polyamides, e.g.,nylons, and polyesters, e.g., PBT.

[0039] Preferred sheath materials include the thermoplastic elastomersdiscussed above. Softer grades of these elastomers can be used when astiff core is provided, e.g., the sheath material may have a hardness aslow as 3 Shore A.

[0040] A suitable method for forming the coextruded filaments is shownin FIG. 5. As shown, the two components are extruded through first andsecond extruders to form a filament, after which the filament is passedthrough a water bath, and through a series of godets. The filament isplaced under light tension as it travels between two drawing godetswhich are rotating at different speeds. The tension applied to thefilament is expressed as the “drawdown ratio”, which is the speeddifferential between the two drawing godets. Preferred drawdown ratiosare from about 1.0 to 7.0. The filament then passes through a relaxinggodet and is collected on a take-up winder. Suitable coextrudedfilaments include, but are not limited to, the following: CompositionDrawdown (Sheath/Core) Volume Ratio Rat. Diameter PEBAX MX1205/ 10:904:1  8 mil Nylon 612 PEBAX MX1205/ 50:50 1:1 or 2:1 55 mil Nylon 612Blend of 90% 10:90 4:1  8 mil PEBAX 2533 and or 10% DYNAFLEX 50:50 1:1or 2:1 55 mil G6712/ Nylon 612 HYTREL 3078/ 10:90 4:1  8 mil Nylon 612or 50:50 1:1 or 2:1 55 mil

[0041] In an alternate embodiment, head portion 14 includes bristles 20integrally joined to spacer 40, which is attached to the base of headportion 14, as shown in FIG. 6. Spacer 40 provides good adhesion ofbristles 20 to head portion 14 and provides support to bristles 18. Theadditional support provided by spacer 40 stiffens bristles 18 bydecreasing the effective length of the bristles, which allows theincorporation of bristles having smaller diameters that more easilypenetrate the interstitial regions of the mouth into the toothbrush.Bristles 18 extend from head portion 14 through spacer 40. Spacer 40 isformed of the elastomeric materials listed above and can be formed ofthe same elastomeric material as used to form the elastomeric bristles20. Spacer 40 and elastomeric bristles 20 at the perimeter of headportion 14 can be molded as one unit. If the bristles 20 and spacer 40are molded as one unit, their diameter is preferably from about 4 mil toabout 200 mil. Elastomeric bristles 20 can extend at angles from spacer40.

[0042] Alternatively, spacer 40 can be recessed into head 14 such thatthe bristle receiving surface 46 of spacer 40 is substantiallycontiguous with surface 44 of head portion 14, as shown in FIG. 7.

[0043] Other embodiments are within the claims. For example, if desired,all of the bristles may be formed of thermoplastic elastomer material.The bristles may be formed of a blend of thermoplastic elastomers.Moreover, the oral brush may include elastomeric bristles havingdifferent relative compositions, e.g., some of the bristles are formedof a first thermoplastic elastomer or blend of elastomers and otherbristles are formed of a different thermoplastic elastomer or blend.Further, the elastomeric bristles may include other polymers, e.g.,plasticizers such as oils, waxes or resins to increase softness, oradditives, e.g., fillers, antioxidants, UV stabilizers, and abrasives orpolishing agents. Suitable polishing agents include particles ofplastic, particles of walnut shells, particles of hardwood, particles ofcorn cob, particles of rubber, calcium carbonate, aragonite clay,orthorhombic clays, calcite clay, rhombohedral clays, kaolin clay,bentonite clay, dicalcium phosphate, dicalcium phosphate anhydrous,dicalcium phosphate dihydrate, tricalcium phosphate, calciumpyrophosphate, insoluble sodium metaphosphate, precipitated calciumcarbonate, magnesium orthophosphate, trimagnesium phosphate,hydroxyapatites, synthetic apatites, alumina, hydrated alumina, hydratedsilica xerogel, metal aluminosilicate complexes, sodium aluminumsilicates, zirconium silicate, silicon dioxide, and combinationsthereof.

1. An oral brush suitable for massaging the gums, comprising: anelongated body; a head portion extending from said body; and a brushportion comprising a plurality of bristles extending from said headportion, said bristles comprising a thermoplastic elastomer having aShore A hardness of 30 or greater.
 2. The oral brush of claim 1 whereinsaid thermoplastic elastomer is selected from the group consisting ofpolyetheramides, polyesters, styrene-ethylene-butylene-styrene blockcopolymers, styrene-butadiene-styrene block copolymers,styrene-isoprene-styrene block copolymers, polyurethanes, polyolefinelastomers, and mixtures thereof.
 3. The oral brush of claim 1 or 2wherein said thermoplastic elastomer has a flexural modulus of at least5 MPa.
 4. The oral brush of claim 1, said oral brush further comprisinga spacer attached to a base of said head portion, said spacer comprisingsaid thermoplastic elastomer and integrally joined to said bristles. 5.The oral brush of claim 1 wherein said brush portion further comprises aplurality of bristles formed of a non-elastomeric material.
 6. The oralbrush of claim 5 wherein said non-elastomeric material is selected fromnylon and polyamides.
 7. The oral brush of claim 6 wherein saidnon-elastomeric material is a crystalline polyphthalamide formed bypolymerization of terphthalic acid, isophthalic acid and adipic acidwith hexamethylene diamine.
 8. The oral brush of claim 5 wherein saidnon-elastomeric material comprises an abrasive additive.
 9. The oralbrush of claim 5, further comprising a spacer attached to a base of saidhead portion, said bristles formed of said non-elastomeric materialextending from said head portion through said spacer.
 10. An oral brushcomprising: an elongated body; a head portion extending from said body;and a brush portion comprising a plurality of bristles extending fromsaid head portion, said bristles comprising a thermoplastic elastomerselected from the group consisting of polyetheramides, polyesters,styrene-ethylene-butylene-styrene block copolymers,styrene-butadiene-styrene block copolymers, styrene-isoprene-styreneblock copolymers, polyurethanes, polyolefin elastomers, and mixturesthereof.
 11. The oral brush of claim 10 wherein said brush portionfurther comprises a plurality of bristles formed of a non-elastomericmaterial.
 12. The oral brush of claim 11 wherein said non-elastomericmaterial is selected from polyamides and polyesters.
 13. The oral brushof claim 12 wherein said non-elastomeric material is a crystallinepolyamide formed by polymerization of terphthalic acid, isophthalic acidand adipic acid with hexamethylene diamine.
 14. The oral brush of claim11 wherein said non-elastomeric material comprises an abrasive additive.15. The oral brush of claim 11, said oral brush further comprising aspacer attached to a base of said head portion, said bristles formed ofsaid non-elastomeric material extending from said head portion throughsaid spacer.
 16. The oral brush of claim 10 wherein said thermoplasticelastomer has a flexural modulus of at least 5 MPa.
 17. The oral brushof claim 10, said oral brush further comprising a spacer attached to abase of said head portion, said spacer comprising said thermoplasticelastomer and integrally joined to said bristles.
 18. An oral brushcomprising: an elongated body; a head portion extending from said body;and a brush portion comprising a plurality of bristles extending fromsaid head portion, said bristles comprising a thermoplastic elastomerhaving a flexural modulus of at least 5 MPa.
 19. The oral brush of claim18, said oral brush further comprising a spacer attached to a base ofsaid head portion, said spacer comprising said thermoplastic elastomerand integrally joined to said bristles.
 20. An oral brush comprising: anelongated body; a head portion extending from said body; and a brushportion comprising, extending from said head portion, a plurality ofbristles comprising a thermoplastic elastomer and a plurality ofbristles comprising a polyphthalamide.
 21. The oral brush of claim 20wherein said polyphthalamide is formed by polymerization of terphthalicacid, isophthalic acid and adipic acid with hexamethylene diamine. 22.The oral brush of claim 21 wherein said polyphthalamide comprises anabrasive additive.
 23. The oral brush of claim 20, said oral brushfurther comprising a spacer attached to a base of said head portion,said spacer comprising said thermoplastic elastomer and integrallyjoined to said bristles comprising said thermoplastic elastomer.
 24. Theoral brush of claim 23, wherein said bristles comprising saidpolyphtalamide extend from said head portion through said spacer.
 25. Amethod of massaging the gums comprising contacting the gums with abristle formed of a thermoplastic elastomer having a Shore A hardness ofat least
 30. 26. A method of massaging the gums comprising contactingthe gums with a bristle formed of a thermoplastic elastomer having aflexural modulus of at least 5 MPa.
 27. A method of massaging the gumscomprising contacting the gums with a bristle formed of a thermoplasticelastomer selected from the group consisting of polyetheramides,polyesters, styrene-ethylene-butylene-styrene block copolymers,styrene-butadiene-styrene block copolymers, styrene-isoprene-styreneblock copolymers, polyurethanes, polyolefin elastomers, and mixturesthereof.
 28. An oral brush comprising: an elongated body; a head portionextending from said body; and a brush portion comprising a plurality ofbristles extending from said head portion, said bristles comprising athermoplastic elastomer sheath, comprising a thermoplastic elastomerselected from the group consisting of polyetheramides, polyesters,styrene-ethylene-butylene-styrene block copolymers,styrene-butadiene-styrene block copolymers, styrene-isoprene-styreneblock copolymers, polyurethanes, polyolefin elastomers, and mixturesthereof, surrounding a non-thermoplastic elastomer core material. 29.The oral brush of claim 28 wherein said bristles are formed bycoextrusion.
 30. The oral brush of claim 28 wherein said core materialis selected from polyamides and polyesters.
 31. The oral brush of claim28 wherein said bristles have a diameter of from 5 to 8 mil.
 32. Theoral brush of claim 28, said oral brush further comprising a spacerattached to a base of said head portion, said spacer comprising saidthermoplastic elastomer and integrally joined to said bristles.
 33. Amethod of making a toothbrush bristle comprising coextruding a pluralityof polymers to form an elongated filament having a plurality of separatephases.
 34. The method of claim 33 wherein one of said polymerscomprises a thermoplastic elastomer.
 35. The method of claim 33 whereinsaid polymers are coextruded in a sheath/core geometry.
 36. The methodof claim 33 further comprising applying tension to said filament to drawthe filament.
 37. The method of claim 36 wherein the tension is appliedat a drawdown ratio of from 1:1 to 7:1.
 38. An oral brush comprising: anelongated body; a head portion extending from said body; and a brushportion comprising a plurality of bristles extending from said headportion, said bristles comprising a thermoplastic elastomer sheathsurrounding a core comprising a thermoplastic elastomer having a higherhardness than said thermoplastic elastomer sheath.
 39. An oral brushcomprising: an elongated body; a head portion extending from said body;and a brush portion comprising a plurality of bristles extending fromsaid head portion, said bristles comprising a blend comprising anelastomeric polymer and a non-elastomeric polymer.
 40. The oral brush ofclaim 39, said oral brush further comprising a spacer attached to a baseof said head portion, said spacer comprising said thermoplasticelastomer and integrally joined to said bristles.
 41. The oral brush ofclaim 39 wherein said elastomeric polymer is selected from the groupconsisting of thermoplastic elastomers and vulcanized rubber-typepolymers.
 42. The oral brush of claim 41 wherein said elastomericpolymer comprises a thermoplastic elastomer selected from the groupconsisting of polyamide thermoplastic elastomers, polyesterthermoplastic elastomers, and olefinic thermoplastic elastomers.
 43. Theoral brush of claim 41 wherein said elastomeric polymer comprises avulcanized rubber-type polymer selected from the group consisting ofnatural rubber, cross-linked polybutadiene, and cross-linkedpolyacrylates and mixtures thereof.
 44. The oral brush of claim 39wherein said elastomeric polymer and said non-elastomeric polymer areprovided in a ratio of from 10:90 to 90:10.